Interplane tunneling magnetoresistance in a layered manganite crystal

The current-perpendicular-to-plane magnetoresistance (CPP-MR) has been investigated for the layered manganite, La2-2xSr1-2xMn2O7 (x = 0,3), which is composed of the ferromagnetic-metallic MnO2 bilayers separated by nonmagnetic insulating block layers, The CPP-MR is extremely large (10(4) percent at 50 kilo-oersted) al temperatures near above the three-dimensional ordering temperature (T-c approximate to 90 kelvin) because of the field-induced coherent motion between planes oi the spin-polarized electrons. Below T-c, the interplane magnetic domain boundary on the insulating block layer serves as the charge-transport barrier, but it can be removed by a low saturation field which gives rise to the low-field tunneling MR as large as 240 percent.